1 files changed, 140 insertions, 0 deletions
diff --git a/clang/lib/AST/Interp/Block.h b/clang/lib/AST/Interp/Block.h
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index 000000000000..97fb9a3ca096
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+++ b/clang/lib/AST/Interp/Block.h
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+//===--- Block.h - Allocated blocks for the interpreter ---------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Defines the classes describing allocated blocks.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_AST_INTERP_BLOCK_H
+#define LLVM_CLANG_AST_INTERP_BLOCK_H
+
+#include "Descriptor.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/ComparisonCategories.h"
+#include "llvm/ADT/PointerUnion.h"
+#include "llvm/Support/raw_ostream.h"
+
+namespace clang {
+namespace interp {
+class Block;
+class DeadBlock;
+class Context;
+class InterpState;
+class Pointer;
+class Function;
+enum PrimType : unsigned;
+
+/// A memory block, either on the stack or in the heap.
+///
+/// The storage described by the block immediately follows it in memory.
+class Block {
+public:
+  // Creates a new block.
+  Block(const llvm::Optional<unsigned> &DeclID, Descriptor *Desc,
+        bool IsStatic = false, bool IsExtern = false)
+      : DeclID(DeclID), IsStatic(IsStatic), IsExtern(IsExtern), Desc(Desc) {}
+
+  Block(Descriptor *Desc, bool IsStatic = false, bool IsExtern = false)
+      : DeclID((unsigned)-1), IsStatic(IsStatic), IsExtern(IsExtern),
+        Desc(Desc) {}
+
+  /// Returns the block's descriptor.
+  Descriptor *getDescriptor() const { return Desc; }
+  /// Checks if the block has any live pointers.
+  bool hasPointers() const { return Pointers; }
+  /// Checks if the block is extern.
+  bool isExtern() const { return IsExtern; }
+  /// Checks if the block has static storage duration.
+  bool isStatic() const { return IsStatic; }
+  /// Checks if the block is temporary.
+  bool isTemporary() const { return Desc->IsTemporary; }
+  /// Returns the size of the block.
+  InterpSize getSize() const { return Desc->getAllocSize(); }
+  /// Returns the declaration ID.
+  llvm::Optional<unsigned> getDeclID() const { return DeclID; }
+
+  /// Returns a pointer to the stored data.
+  char *data() { return reinterpret_cast<char *>(this + 1); }
+
+  /// Returns a view over the data.
+  template <typename T>
+  T &deref() { return *reinterpret_cast<T *>(data()); }
+
+  /// Invokes the constructor.
+  void invokeCtor() {
+    std::memset(data(), 0, getSize());
+    if (Desc->CtorFn)
+      Desc->CtorFn(this, data(), Desc->IsConst, Desc->IsMutable,
+                   /*isActive=*/true, Desc);
+  }
+
+protected:
+  friend class Pointer;
+  friend class DeadBlock;
+  friend class InterpState;
+
+  Block(Descriptor *Desc, bool IsExtern, bool IsStatic, bool IsDead)
+    : IsStatic(IsStatic), IsExtern(IsExtern), IsDead(true), Desc(Desc) {}
+
+  // Deletes a dead block at the end of its lifetime.
+  void cleanup();
+
+  // Pointer chain management.
+  void addPointer(Pointer *P);
+  void removePointer(Pointer *P);
+  void movePointer(Pointer *From, Pointer *To);
+
+  /// Start of the chain of pointers.
+  Pointer *Pointers = nullptr;
+  /// Unique identifier of the declaration.
+  llvm::Optional<unsigned> DeclID;
+  /// Flag indicating if the block has static storage duration.
+  bool IsStatic = false;
+  /// Flag indicating if the block is an extern.
+  bool IsExtern = false;
+  /// Flag indicating if the pointer is dead.
+  bool IsDead = false;
+  /// Pointer to the stack slot descriptor.
+  Descriptor *Desc;
+};
+
+/// Descriptor for a dead block.
+///
+/// Dead blocks are chained in a double-linked list to deallocate them
+/// whenever pointers become dead.
+class DeadBlock {
+public:
+  /// Copies the block.
+  DeadBlock(DeadBlock *&Root, Block *Blk);
+
+  /// Returns a pointer to the stored data.
+  char *data() { return B.data(); }
+
+private:
+  friend class Block;
+  friend class InterpState;
+
+  void free();
+
+  /// Root pointer of the list.
+  DeadBlock *&Root;
+  /// Previous block in the list.
+  DeadBlock *Prev;
+  /// Next block in the list.
+  DeadBlock *Next;
+
+  /// Actual block storing data and tracking pointers.
+  Block B;
+};
+
+} // namespace interp
+} // namespace clang
+
+#endif